VOLTAGE-TUNABLE COLOR MULTILAYER ORGANIC LIGHT-EMITTING DIODE

Organic electroluminescent diodes with a double-heterostructure of ind ium-tin-oxide (ITO) substrate/aromatic diamine (TPD)/8-hydroxyquinolin e aluminum (Alq(3))/perylene bisimide pigment (PBP)/Mg/Ag have been fa bricated by successive vapor deposition. Their electroluminescence (EL ) for thin layers of PBP varies from the orange dominated by the red e mission of PBP to greenish-yellow with a strong contribution of the gr een emission of Alq, as voltage increases. The relative contribution o f the red emission increases with increasing voltage for the structure s with thick PBP layers. The tuning of the EL color is explained in te rms of electric field-induced quenching of excited states and voltage evolution of the recombination zone in PBP. (C) 1996 American Institut e of Physics.